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Viscera:External genitalia (male and female)
Perineal body: The central tendon of the perineum, is a midline fibromuscular mass to which several muscles gain attachment. It is the posterior border of the perineal membrane, lies between anal canal and vagina. The rectovaginal septum blends into it. * external anal sphincter * pubovaginalis * bulbospongiosus * superficial and deep transverse perineal muscle The perineal membrane is an anatomical term for the fibrous membrane in the perineum, analogous to inferior fascia of urogenital diaphragm". It is the superior border of the superficial perineal pouch, and the inferior border of the deep perineal pouch. It is triangular in shape, and about 4 cm. in depth. * Apex: directed forward, and is separated from the arcuate pubic ligament by an oval opening for the transmission of the deep dorsal vein of the penis. ** Attachments include crura of the clitoris (in female) and covered by ischiocavernosus muscle. Medial to the crus is a erectile tissue, bulb of the vestibule that join in front of the urethra orifice. These are covered by the bulbospongiosus muscle that extend from perineal body to clitoris. * Lateral margins: attached on either side to the inferior rami of the pubis and ischium. * Base: ** Directed toward the rectum, and perineal body. ** Deep transverse perineal muscle extend from the ischial ramus to the perineal body forming the posterior margin of the base. The muscle merges with the external/internal anal sphincters. Perforations * Urethra: 2.5 cm below the pubic symphysis, The prostatic urethra forms the membranous urethra when it enters the deep perineal pouch and when it pierces the perineal membrane, it becomes the penile urethra. * Vagina (in female) * The arteries to the bulb and the ducts of the bulbourethral glands (the glands sit on each side of the membranous urethra, and ducts pass through the membrane to open into the bulb of the penile urethra) * Deep arteries of the penis, one on either side * Dorsal arteries and nerves of the penis * Perineal vessels and nerves: at the base * Deep dorsal vein of the penis The sphincter of the urethra - is pear-shaped striated muscles, sitting above the perineal membrane, surrounding the membranous portion of the urethra. It is supplied by perineal branch of pudendal nerve. Penis has a root and a body. Root: attached to the inferior surface o the perineal membrane, and consists of bulb of the penis with a crus on each side. Crus is attached to the angle between the perineal membrane and margin of the ischiopubic ramus. * The crus extend forward as the corpus cavernosum * The bulb extend forward as the corpus spongiosum Body: the main structure of the penis formed by two corpora cavernosa and single corpus spongiosum. Each is bounded by a fibrous sheath the tunica albuginea. * Two corpora cavernosa: Main erectile bodies ** On dorsal surface of penis ** Diverge at root of penis (crura) and are invested by ischiocavernosus muscles ** Fibrous trabeculae pass into the corpora, dividing their substance into multiple cavernous space. ** Multiple fenestrations between corpora, creating multiple anastomotic channels ** Between corpora there is connective tissue septum * One corpus spongiosum: Contains urethra ** On ventral surface, in groove created by corpora cavernosa ** Becomes penile bulb (urethral bulb) at root and is invested bulbospongiosus muscle ** Forms glans penis distally ** Also erectile tissue but of far less importance Three corpora is encircled by the deep fascia of the penis (an extension of the deep perineal fascia). Outside this is the superficial fascia of the penis (Buck's fascia) which is a cylindrical prolongation of Colle's fascia. At its midline lies, the superficial dorsal vein accompany by lymphatics from the skin and anterior part of the urethra. Midline deep dorsal vein with dorsal artery on either side and more lateral dorsal nerve lies in the deep fascia of the penis. Prepuce - foreskin, that partly overlaps the glands and folds back to attach to the neck of the glans. Musculature of the penis (superficial perineal muscles): all muscles are supplied by the perineal branch of the pudendal nerve. * b'ulbospongiosus:' arise from perineal body, unite in a midline raphe. The fibres pass around the bulb and insert into the perineal membrane and root of penis, with more anterior fibres reaching the spongiosum and cavernosus. It function to empty the urethra at the end of micturition, ejaculation and erection. * ischiocavernosus: arise from posterior part of the perineal membrane, and from ischial ramus pass to the aponeurosis on the surface of the corpus cavernosum. * superficial transverse perineal muscle: arise from the ischial tuberosities and insert into the perineal body. Arterial supply Three pairs of branches from the internal pudendal arteries * artery to the bulb: the corpus spongosium including the glans * deep artery of the penis: the corpus cavernosum and gives helicine arteries * dorsal artery: runs between tunica and buck fascia and supply skin, fascia and glans. * superficial external pudendal branches of the femoral arteries Venous return * Veins accompany arteries of same name and join the internal pudendal veins * Mostly by deep dorsal vein that enters the vesicoprostatic venous plexus. * Superficial dorsal vein drains the dorsal skin of penis and divides to join the superficial external pudendal tributaries of the greater saphenous vein. Lymph supply * penile skin pass to superficial inguinal nodes * glans and corpora pass to deep inguinal nodes Nerve supply * pudendal nerves: via posterior scrotal and dorsal nerves to skin of penis * ilioinguinal nerve: small area on the dorsumof proximal penis * perineal nerve (from pudendal): bulbocavernosus and ischiocavernosus muscle * sympathetic nerves are from L1 segment of spinal cord via superior and inferior hypogastric plexuses (for ejaculation) * parasympathetic from pelvic splanchnic nerves (for erection) Scrotum '''is a pouch of skin that contains the testes and spermatic cords. The subcutaneous tissue has no fat, but contains dartos muscles, which is a smooth muscle. It is supplied by sympathetic fibres, carried by genital branch for the genitofemoral nerve. Blood supply: '''Arterial supply * superficial and deep external pudendal arteries (from femoral) * scrotal branches of perineal artery Venous drainage * external pudendal veins, superficial and deep to the great saphenous vein formed by two small corpora cavernosa and the anterior ends of the bulbs of the vestibule, its free extremity is highly sensitive to sexual stimulation. Lymph drainage: superficial inguinal nodes Nerve supply: * ilioinguinal nerve and genital branch of genital branch of genitofemoral nerve (L1) to anterior 1/3 of scrotal * scrotal branches of perineal nerve and perineal branch of the posterior femoral cutaneous nerve Female urogenital region Mons pubis - mound of hairy skin, fat in front of the pubic symphysis Labia major - fatty cutaneous folds forming the boundary of the pudendal cleft. The round ligament of the uterus ends in the anterior part of each labium. Labia minor - cutaneous folds without fat lying internal to the labia majora and forming boundaries of the vestibule. The front split and unite to form the prepuce and frenulum of the clitoris, while at the back they unite by a small skin fold Clitoris - lies at the front ends of the labia minora. Formed by two miniature corpora cavernosa and the anterior ends of the bulb of the vestibule. Vestibule: contains the external urethral meatus, vaginal orifice and ducts of the greater vestibular glands